Photographic projection arrangements utilizing a printer normally work with copy material of standardized width, which limits the maximum size of the copies which can be produced. Oversized copies, for example, posters and the like, are produced by assembly from smaller partial pictures. The original images are therefor divided into a number of partial image originals of suitable size, and a set of partial image copies is produced from these partial image originals by sequential projection onto the normally band shaped copy material and by subsequent developing of the copy material in a pass-through developing arrangement. They are then cut to size and assembled to the desired compound picture.
The division of the image original is normally carried out according to a matrix schematic with lines and columns. The lines of the matrix-type arrangement extend parallel to the respective upper and lower edges of the individual partial image originals, the columns extend parallel to the lateral edges of the partial image originals. The individual partial image originals are exposed in the same orientation in a linear arrangement one after the other onto the normally band shaped copy material. The projection of the individual partial image originals is thereby carried out such that the lateral edges of the partial image originals are parallel to the longitudinal edges of the copy material defining the width thereof or in the extreme case coincide therewith. The longitudinal edges of the copy material extend parallel to the transport direction of the copy material through the printer and the pass-through developing arrangement. This definition applies accordingly in the case of sheet material.
Often undesirable or even un-tolerable color and/or density differences occur in pictures manufactured in this manner and composed of individual partial images in the region of the separation lines between the individual columns of the picture, which are caused by the practically unavoidable inhomogeneities of the pass-through developing arrangement transverse to the transport direction. While these inhomogeneities are practically unimportant in the normal case, i.e. during the manufacture of individual photographic copies of common format, they however are of greatly negative influence during the manufacture of composite pictures.